Mr. Sims and Mr. Sargent neither prescribe cures nor forecast the future. Nor do they deal in the sound bites of talking heads on cable TV. They are reluctant celebrities, men whose work can baffle even Ph.D.’s.

So it comes as a surprise, not least to Mr. Sims and Mr. Sargent, that these two now find themselves thrust into an uncomfortable spotlight. Conservative voices, like the editorial page of The Wall Street Journal, have claimed them as their own. The men’s work on economic cause and effect and the theory of rational expectations — which maintains that people use all the information available in making economic decisions — proves that Keynes had it wrong, these commentators say.

It would be a provocative thesis — if it were true. But Mr. Sims and Mr. Sargent say their work is being misread. Both, in fact, are longtime Democrats who maintain that government can, and should, play a role in economic affairs.